This Project will evaluate the effectiveness of amitriptyline and mexilitene in relieving pain symptoms in patients with HIV-related painful neuropathy. The study is a three arm parallel group, placebo controlled clinical trial, with subjects randomly assigned to receive on of three treatments: amitriptyline, mexilitene or placebo. The does will be titrated upward during the initial 4 weeks of the trial, then maintained for the second four weeks of study. Benztropine will be used as an "active placebo". Response parameters will include a standardized neurological exam, a global assessment of pain response, and the requirement for additional analgesic agents. Serum levels of study drugs will be determined. It is calculated that 80 patients per arm (240 subjects total) will be required.